Optimise slasher DB layout and switch to MDBX (sigp#2776)

## Issue Addressed

Closes sigp#2286
Closes sigp#2538
Closes sigp#2342

## Proposed Changes

Part II of major slasher optimisations after sigp#2767

These changes will be backwards-incompatible due to the move to MDBX (and the schema change) 😱 

* [x] Shrink attester keys from 16 bytes to 7 bytes.
* [x] Shrink attester records from 64 bytes to 6 bytes.
* [x] Separate `DiskConfig` from regular `Config`.
* [x] Add configuration for the LRU cache size.
* [x] Add a "migration" that deletes any legacy LMDB database.

.github/workflows/test-suite.yml

@@ -12,7 +12,7 @@ env:
   # Deny warnings in CI
   RUSTFLAGS: "-D warnings"
   # The Nightly version used for cargo-udeps, might need updating from time to time.
-  PINNED_NIGHTLY: nightly-2021-06-09
+  PINNED_NIGHTLY: nightly-2021-12-01
 jobs:
   target-branch-check:
     name: target-branch-check
@@ -54,6 +54,12 @@ jobs:
       run: npm install -g ganache-cli
     - name: Install make
       run: choco install -y make
+    - uses: KyleMayes/install-llvm-action@v1
+      with:
+        version: "13.0"
+        directory: ${{ runner.temp }}/llvm
+    - name: Set LIBCLANG_PATH
+      run: echo "LIBCLANG_PATH=$((gcm clang).source -replace "clang.exe")" >> $env:GITHUB_ENV
     - name: Run tests in release
       run: make test-release
   beacon-chain-tests:

Cross.toml

@@ -2,3 +2,14 @@
 passthrough = [
     "RUSTFLAGS",
 ]
+
+# These custom images are required to work around the lack of Clang in the default `cross` images.
+# We need Clang to run `bindgen` for MDBX, and the `BINDGEN_EXTRA_CLANG_ARGS` flags must also be set
+# while cross-compiling for ARM to prevent bindgen from attempting to include headers from the host.
+#
+# For more information see https://github.com/rust-embedded/cross/pull/608
+[target.x86_64-unknown-linux-gnu]
+image = "michaelsproul/cross-clang:x86_64-latest"
+
+[target.aarch64-unknown-linux-gnu]
+image = "michaelsproul/cross-clang:aarch64-latest"

Dockerfile

@@ -1,5 +1,5 @@
-FROM rust:1.53.0 AS builder
-RUN apt-get update && apt-get -y upgrade && apt-get install -y cmake
+FROM rust:1.56.1-bullseye AS builder
+RUN apt-get update && apt-get -y upgrade && apt-get install -y cmake libclang-dev
 COPY . lighthouse
 ARG PORTABLE
 ENV PORTABLE $PORTABLE

beacon_node/beacon_chain/tests/block_verification.rs

@@ -830,11 +830,7 @@ fn block_gossip_verification() {
 fn verify_block_for_gossip_slashing_detection() {
     let slasher_dir = tempdir().unwrap();
     let slasher = Arc::new(
-        Slasher::open(
-            SlasherConfig::new(slasher_dir.path().into()).for_testing(),
-            test_logger(),
-        )
-        .unwrap(),
+        Slasher::open(SlasherConfig::new(slasher_dir.path().into()), test_logger()).unwrap(),
     );
 
     let inner_slasher = slasher.clone();

beacon_node/src/cli.rs

@@ -515,12 +515,20 @@ pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
             Arg::with_name("slasher-max-db-size")
                 .long("slasher-max-db-size")
                 .help(
-                    "Maximum size of the LMDB database used by the slasher."
+                    "Maximum size of the MDBX database used by the slasher."
                 )
                 .value_name("GIGABYTES")
                 .requires("slasher")
                 .takes_value(true)
         )
+        .arg(
+            Arg::with_name("slasher-att-cache-size")
+                .long("slasher-att-cache-size")
+                .help("Set the maximum number of attestation roots for the slasher to cache")
+                .value_name("COUNT")
+                .requires("slasher")
+                .takes_value(true)
+        )
         .arg(
             Arg::with_name("slasher-chunk-size")
                 .long("slasher-chunk-size")

beacon_node/src/config.rs

@@ -510,6 +510,12 @@ pub fn get_config<E: EthSpec>(
             slasher_config.max_db_size_mbs = max_db_size_gbs * 1024;
         }
 
+        if let Some(attestation_cache_size) =
+            clap_utils::parse_optional(cli_args, "slasher-att-cache-size")?
+        {
+            slasher_config.attestation_root_cache_size = attestation_cache_size;
+        }
+
         if let Some(chunk_size) = clap_utils::parse_optional(cli_args, "slasher-chunk-size")? {
             slasher_config.chunk_size = chunk_size;
         }